LOUISVILLE, Kentucky (AP) -- Stepping into an issue on the political fringe, a Republican Senate candidate spoke at a Kentucky rally meant to build support for legal cockfighting, a bloody practice illegal under U.S. law.

Matt Bevin, the conservative tea party-backed challenger to Senate Minority Leader Mitch McConnell, portrayed the event last Saturday as a states' rights rally, but his appearance among cockfight backers prompted one animal-rights group to call on Bevin to withdraw from the May 20 Republican Party primary.

The McConnell campaign scoffed at Bevin's description of the event.

"Only Matt Bevin would go to a cockfighting rally and claim he didn't know what they were doing there," said McConnell's campaign spokeswoman, Allison Moore.

Bevin did not respond to several requests for comment Friday.

But he told WHAS-AM in Louisville he's never been to a cockfight and doesn't condone it.

Bevin also indicated in the radio interview that the U.S. government should give way to states on the matter. The federal bill that sets farm policy also prohibits knowingly attending an animal fighting venture, such as a cockfight.

McConnell's vote in favor of the bill irked cockfighting enthusiasts in his state.

It is a misdemeanor in Kentucky to enter a bird in a cockfight -- in which roosters outfitted with spurs fight to the death while spectators wager on the outcome. The issue surfaces in Kentucky during occasional police raids on cockfighting rings.

Bevin, a Louisville businessman and political newcomer, is facing long odds in challenging McConnell, the longest-serving senator in Kentucky's history.

McConnell has a huge fundraising advantage. Bevin portrays McConnell as an out-of-touch Washington insider. The winner of the Republican primary will likely face Democratic front-runner Alison Lundergan Grimes in November.

Bevin never brought up cockfighting during his speech before about 700 people at the private rally at Corbin in southeastern Kentucky, but other speakers advocated for legal cockfighting after Bevin had left, said Craig Davis, president of the United Gamefowl Breeders Association. Other issues that came up included federal spending and federal involvement in personal lives, he said.

Animal rights activists were furious.

"Matt Bevin showed appalling judgment in associating himself with this band of lawbreakers and perpetrators of unspeakable animal cruelty," said Michael Markarian, president of The Humane Society Legislative Fund.